Spectral discharge tube



March 29, 1932. A. E. JACOBSEN SPECTRAL DISCHARGE TUBE Filed Feb. 25' 1950 INVENTOR lglffiffiT E. J cOEsE/v ATTORNEY Patented Mar. 129, 1932 UNITED STATES" PATENT OFFICE ALBERT EDWIN JACOBS EN', OF SEATTLE, WASHINGTON, ASSIGNOR TO LUMIINOUS TUBE LIGHTING CORPORATION, A CORPORATION OEWASHINGTON SPECTRAL DISCHARGE TUBE Application filed February 25, 1930. Serial No. 431,298.

This invention relates to spectral discharge tubes and it has for its principal object to provide a luminous tube of the above character which will produce a white light without the generation of any perceptible heat; that is, a luminous tube that produces a light which for all practical purposes, is the full equivalent of natural daylight and which is substantially a cold light.

It will here be stated that, during the pastfewyears, luminous tubes of that character generally referred to as gaseous conductor tubes, have gone into extensive use for signs M and outside displays because of the attractiveness of their colors and because of their relatively small consumption of electricity. Such luminous tubes, however, have not' been adapted to interior lighting, or tothe illumi: nation of displays, such as those placed in showcases, because the color of the light produced prohibits the display of goods in their true colors, and, furthermore, a certain degree of heat is emitted from the tubes which renders them extremely undesirable for most interior uses, and especially for show case illumination.

In view of the above mentioned and other disadvantages inherent in the now commonly used spectral discharge tubes, especially those known as, or referred to, as neon tube's, it has been the principal object of the present invention to produce a spectral discharge tube using a gaseous conductor which will produce white light under action of ultra violet rays and which is eminently suitable and desirable not only for the formation of sign characters and decorative displays, but

also is most satisfactory for show cases lighting, and for general interior illumination, and which uses less electric current,

In carrying out the present invention, I utilize a gaseous product, which is a combination of gases having a-carbon base, as the conductor for the electric circuit within the glass tube; these gases being introduced into the tube after'the latter has been properly evacuated, and after it has been suitably treated for clearing its interior surfaces of moisture and alloccluded gases, it being understood, of course, that the opposite terminals or ends of thctube are provided with order to effect its illumination,

More specifically described, the various steps preliminary to and in carrying out the present invention are as follows: 1

First, a suitable tube, preferably of soda glass, is selected, this kind of glass being most desired by reason of the absence of any mineral, or substance in its composition which would give color to the light passing through it. The tube is first properly constructed with terminal electrodes and is then'treated for the purpose of clearing or cleaning the electrodes and the inner wall surfaces of all moisture and occluded gases. A preferred treatment consists of first evacuating the tube in any suitable manner to produce a vacuum of approximately .001. Preferably a vacuuni pump having direct connection with the tube would be used for this purpose 'in order that the application of vacuum may be done gradually and,by the use of pressure gauges i then may be containedin the tube or walls of the tube and electrodes are withdrawn by providing an open connection between the tube and a container in which there are alter nate layersof glass wool and activated charcoal, or any other substance which will serve ing phosphoric acid or mono hydrated phosphoric acid or meta phosphoric acid, or other acids of the phosphorus group, so that gas from the latter will be drawn into the evacuated tube. This gas carries with it small particles of phosphorus which are deposited on the tube surface to seal the pores and, in the illtillilate use of the tube, adds brilliancy to the 1g At this time, an electric circuit is closed through the tube and it will be illuminated by reason of the previous introduction of the treating gas. The tube is now connected again with the vacuum pump, and at first it will be observed that the glow of light will entirely fill the tube up to and beyond the electrodes, but this glow will gradually recede, as the evacuation progresses, and when the glow has cleared away up to the faces of the electrodes, the connections with the tube are closed.

While I have mentioned certain definite means for evacuating the tube and have specified certain chemicals and gases for its preliminary treatment, I do not wish to be confined to these since this treatment while desirable and beneficial is not the predominating feature of the present invention and might be carried out in other ways which will clear the glass of moisture and occluded gases and then seal the pores.

Following this preparatory treatment of the tube, a gaseous product, which is a mixture of carbon dioxide gas, acetylene gas and hydrogen gas, is introduced thereunto; this being the gaseous conductor which produces the white light. Preferably these gases would be in the proportion of one-eighth part of acetylene, one-tenth part hydrogen gas and the remainder of carbon dioxide gas, but it is to be understood that these proportions may be varied within certain limits without undesirable results.

After the gas mixture above has been introduced into the tube, the tube is again connected with theevacuating pump, and the vacuum in the tube is drawn until the tube attains a desired, or its maximum brilliancy, and the cathode dark spaces have disappeared. At this time, the tubulation is sealed off in the usual manner'and the tube is then ready for its commercial use.

In carrying out the process, it has been found that results which are satisfactory to a.

certain degree may be obtained by use of vari ous other mixtures of gas for the final filling of the tubes. For example, following the phosphoric acid treatment of the tube, it may be charged with a mixture of carbon dioxide gas and a relatively small amount of hydrogen gas, which should be sufficient to correct the lack of red rays in the spectrum.

Another example:

Following the preliminary treatment, the tube may be filled with.

a mixture of acetylene gas and a small amount of hydrogen gas.

Still another example: Following the preliminary treatment, the tube may be filled with a mixture of carbon dioxide and acetylene gas.

Other carbon compounds, or vapors of carbon chemicals and gases, such as gasolene, or alcohol, or benzene may be used but at present are not thought to be as desirable on account of their lack of permanency in use.

To better explain the preferred process, I have illustrated, in the single figure of the drawing a satisfactory apparatus for treating and filling the tubes. In this drawing, 1 designates what may be any suitable vacuum pump, or device, and .2 is a tube that leads from the pump along a supporting rack 3 and has connection at its end with a tube 4 which is the tube to be treated and filled. 5, 6 and 7, respectively, designate tubes, or containers, which respectively contain the calcium chloride, phosphorus pentoxide, and the alternate layers of glass wool and activated charcoal; 8 designates the container for the phosphoric acid; and 9 and 10 are flasks, or containers, of the prepared mixture of gases for finally filling the tubes. These various tubes, or containers, 5, 6, 7, 8, 9 and 10, are individually connected with the tube 2 through the medium of short connections that are valved as at 11. Other valves 12 and 13 are provided in the tube 2 so that the pump may be closed off from the system and also that the various containers may be collectively closed off. 14 and 15 designate the enlarged terminal portions at opposite ends of the tube 4 that is being prepared and 16-16 designates the electrodes therein to which circuit wires 17 and 18 are connected.

This particular apparatus permits of an easy, quick and methodical treating and filling of the tubes by following the procedure previously outlined. Tubes that are treated and filled in the above manner will producea light, which, for all practical purposes, is absolutely white and is without heat. Such tubes are especially desirable for show case lighting where heat cannot be permitted and where daylight eflect is desired. They are suitable also for signs, displays, house numbers, and for general illumination.

Having thus described my invention, what A I claim as new therein and desire to secure by Letters-Patent, is:

1., A spectral discharge tube having a gaseous conductor comprising a mixture of carbon dioxide gas and hydrogen gas.

2. A spectral discharge tube having a gaseous conductor comprising a mixture of carbon dioxide as and acetylene gas.

3. A spectral discharge tube having a gaseous conductor comprising a mixture of acetylene gas and h drogen gas.

4. A spectral discharge tube having a gaseous conductor consisting of a combination of carbon dioxide, acetylene and hydrogen gases.

5. A spectral discharge tube having a gaseous conductor consisting of a comblnation of one-eighth part acetylene gas onetenth part hydrogen gas and reminder of carbon dioxide gas.

6.A spectral discharge tube of the character described having its inner surface treated with hosphoric acid and filled with a gaseous con uctor consisting of a combination of carbon gases which will fluoresce white under action of ultra violetlight.

7 The method of preparing a spectral discharge tube which consists of preparing the tube with terminal electrodes, treating'the tube interiorly to remove 1 all moisture and occluded gases, treating the tube surface with phosphonc acid gas, evacuating the tube and then filling with a gaseous conductor consistin of a combination of carbon gases.

7 igned at Seattle, Washington, this 20th day of February, 1930.

ALBERT EDWIN JACOBSEN. 

